Racing vehicles, particularly those for special class racing, such as single cylinder flathead engined vehicles, are subject to racing rules that specify a maximum distance between the exhaust port on the engine's head and the end of the vehicle chassis.
It is known in the art to specially design multiple bend exhaust pipes for two cycle engines, and it is also known in the art to specially design multiple bend exhaust pipes for four cycle engines for the purpose of reducing noise or for proper fitment. It is known in the prior art to provide straight exhaust pipes having successive sections of differing diameters, but it is not known in the prior art to have successive sections of differing diameters in combination with the use of two U shaped bends for meeting overall length or other requirements for exhaust pipes in conjunction with increasing performance.
For example, U.S. Pat. No. 3,590,947 to Latch et al. shows a muffler with a double U shape path, in which many complex U shaped sections of a single inner diameter within each U section are used in connection with baffles and alcoves, and in which entry and exit sections are provided that have larger inner diameters than the U shaped section. The muffler of Latch et al. is designed primarily to reduce noise and to reduce back pressure in the engine cylinders through the use of passageways having larger cross-sectional areas than the inlet port and outlet port of the muffler. The muffler of Latch et al. does not include an exhaust pipe for use with or without a muffler, the pipe having a double U shape path with varying inner diameters within the U sections for producing vacuum pulses and other flow characteristics that match the engine intake and exhaust valve opening over selected engine speed ranges and thereby enhance four cycle engine performance. In addition, the muffler of Latch et al. is not designed particularly for use within single cylinder flathead or other racing engine constraints.
U.S. Pat. No. 4,381,045 to Buchwalder describes a double U shaped exhaust gas silencer that uses tubes of uniform inner diameter and end chambers having end walls with rounded and hollow bosses for redirecting gas flow. The exhaust silencer of Buchwalder does not include an exhaust pipe for use with or without a muffler, the pipe having only a double U shape path with varying inner diameters within the U sections for producing vacuum pulses and other flow characteristics that match the engine intake and exhaust valve opening over selected engine speed ranges and thereby enhance four cycle engine performance. In addition, the silencer of Buchwalder is not designed particularly for use within single cylinder flathead or other racing engine constraints.
U.S. Pat. No. 1,514,441 to Culp shows an exhaust trap having multiple headers and cooperating tubes and is particularly for use with a gas or locomotive engine. The exhaust trap of Culp is designed to create a vacuum for pull on the piston when the exhaust port opens. The exhaust trap of Culp does not include an exhaust pipe for use with or without a muffler, the pipe having only a double U shape path with varying inner diameters within the U sections for producing vacuum pulses and other flow characteristics that match the engine intake and exhaust valve opening over selected engine speed ranges and thereby enhance four cycle engine performance. In addition, the exhaust trap of Culp is not designed particularly for use within single cylinder flathead or other racing engine constraints.
U.S. Pat. No. 3,462,947 to Nowak shows an exhaust system particularly designed for increasing the efficiency of two stroke engines. The system of Nowak has divergent and convergent cones fitted within a sleeve, and sound muffling baffles and a reflector plate. The exhaust system of Nowak does not include an exhaust pipe for use with or without a muffler, the pipe having a double U shape path with varying inner diameters within the U sections for producing vacuum pulses and other flow characteristics that match the engine intake and exhaust valve opening over selected engine speed ranges and thereby enhance four cycle engine performance. In addition, the exhaust system of Nowak is not designed particularly for use within single cylinder flathead or other racing engine constraints.
U.S. Pat. No. 3,665,712 to Tenney shows an exhaust system particularly designed for reducing the noise of two stroke engines in particular applications that limit the size of the system, such as chain saws. The exhaust system of Tenney includes a resonance chamber that has at least one change of direction or bend, and a silencing section located within the crook of the bend. The exhaust system of Tenney does not include an exhaust pipe for use with or without a muffler, the pipe having a double U shape path with varying inner diameters within the U sections for producing vacuum pulses and other flow characteristics that match the engine intake and exhaust valve opening over selected engine speed ranges and thereby enhance four cycle engine performance. In addition, the exhaust system of Tenney is not designed particularly for use within single cylinder flathead or other racing engine constraints.
U.S. Pat. No. 3,690,406 to Weiss shows an exhaust noise silencer (FIG. 1), which includes a pipe having multiple U shaped bends for reducing exhaust noise without using a baffle arrangement. The exhaust noise silencer of Weiss does not include an exhaust pipe for use with or without a muffler, in which the pipe has a double U shape path with varying inner diameters within the U sections for producing vacuum pulses and other flow characteristics that match the engine intake and exhaust valve opening over selected engine speed ranges and thereby enhance four cycle engine performance. In addition, the exhaust noise silencer of Weiss is not designed particularly for use within single cylinder flathead or other racing engine constraints.
U.S. Pat. No. 3,842,599 to Ehlen shows an exhaust system, which is particularly designed for two stroke engines, that includes at least one working chamber, a tubular member with an expansion chamber for containing gases during the initial scavenging of the chamber, and a U shaped section. In addition, the system of Ehlen includes a contraction section for reflecting a positive pressure wave back to the exhaust port to retain combustible fluid within the working chamber. The exhaust system of Ehlen does not include an exhaust pipe for use with or without a muffler, the pipe having simply a double U shape path with varying inner diameters within the U sections for producing vacuum pulses and other flow characteristics that match the engine intake and exhaust valve opening over selected engine speed ranges and thereby enhance four cycle engine performance. In addition, the exhaust system of Ehlen is not designed particularly for use within single cylinder flathead or other racing engine constraints.
U.S. Pat. No. 3,968,854 to Gordon et al. shows a low noise level muffler for small engines, the muffler having an inlet tube and multiple chambers for dispersing and recombining exhaust gases to reduce noise. The muffler of Gordon et al. does not include an exhaust pipe for use with or without a muffler, the pipe having a double U shape path with varying inner diameters within the U sections for producing vacuum pulses and other flow characteristics that match the engine intake and exhaust valve opening over selected engine speed ranges and thereby enhance four cycle engine performance. In addition, the muffler of Gordon et al. is not designed particularly for use within single cylinder flathead or other racing engine constraints.
U.S. Pat. No. 4,290,501 to Tanaka shows an exhaust silencer for reducing the exhaust noise of small, low-speed two cycle engines for vehicles having minimal space for the silencer, such as golf cars. The silencer of Tanaka includes a silencer chamber, an exhaust pipe with a U shape, and a generally conical expansion section extending into an encompassing chamber. The silencer of Tanaka does not include an exhaust pipe for use with or without a muffler, the pipe having a double U shape path with varying inner diameters within the U sections for producing vacuum pulses and other flow characteristics that match the engine intake and exhaust valve opening over selected engine speed ranges and thereby enhance four cycle engine performance. In addition, the silencer of Tanaka is not designed particularly for use within single cylinder flathead or other racing engine constraints.
U.S. Pat. No. 4,360,076 to Suyama shows a muffler having an inlet pipe, outlet pipe, and main body, the pipes generally reversing the direction of exhaust flow and including apertures and other features for improving performance and reducing noise. The muffler of Suyama does not include an exhaust pipe for use with or without a muffler, the pipe having a double U shape path with varying inner diameters within the U sections for producing vacuum pulses and other flow characteristics that match the engine intake and exhaust valve opening over selected engine speed ranges and thereby enhance four cycle engine performance. In addition, the muffler of Suyama is not designed particularly for use within single cylinder flathead or other racing engine constraints.
U.S. Pat. No. 4,735,283 to Macaluso shows muffler with flow direction plates, in which the flow direction plates are curved such that a generally double-U shaped exhaust path is produced. The low back pressure acoustic muffler of Macaluso is intended to provide improved performance simply by directing flow in a curved path at the muffler ends using curved plates. The muffler of Macaluso does not include an exhaust pipe for use with or without a muffler, the pipe having a double U shape path with varying inner diameters within the U sections for producing vacuum pulses and other flow characteristics that match the engine intake and exhaust valve opening over selected engine speed ranges and thereby enhance four cycle engine performance. In addition, the muffler of Macaluso is not designed particularly for use within single cylinder flathead or other racing engine constraints.
U.S. Pat. No. 5,392,602 to Matsumoto shows an exhaust emission control device for scooter applications. The device of Matsumoto includes a single U shaped section and expansion chambers to allow sufficient length within the muffler to improve engine performance but reduce heat. The device of Matsumoto does not include an exhaust pipe for use with or without a muffler, the pipe having a double U shape path with varying inner diameters within the U sections for producing vacuum pulses and other flow characteristics that match the engine intake and exhaust valve opening over selected engine speed ranges and thereby enhance four cycle engine performance. In addition, the device of Matsumoto is not designed particularly for use within single cylinder flathead or other racing engine constraints.
U.S. Pat. No. 5,559,310 to Hoover et al. shows muffler for air operated pumps, the muffler having a double flow path reversal in a generally double U shape for reducing noise without restricting pump performance. The muffler of Hoover et al. does not include an exhaust pipe for use with or without a muffler, the pipe having a double U shape path with varying inner diameters within the U sections for producing vacuum pulses and other flow characteristics that match the engine intake and exhaust valve opening over selected engine speed ranges and thereby enhance four cycle engine performance. In addition, the muffler of Hoover et al. is not designed particularly for use within single cylinder flathead or other racing engine constraints.
None of the prior art identified provides an exhaust pipe for use with four cycle engines for racing vehicles that is designed to increase horsepower within established racing or other size constraints through use of a pipe having a profile of a double U shaped path having varying inner diameters within various sections.
There is therefore a need for an exhaust pipe for overcoming these limitations and others by providing for increased horsepower within established racing or other constraints.